In vitro analysis of the cytotoxic effect of two different sizes ITER-like tungsten nanoparticles on human dermal fibroblasts

Background

Based on the current configuration of the International Thermonuclear Experimental Reactor, tungsten (W) was chosen as the armour material. Nevertheless, during operation, the expected power and temperature of plasma can trigger the formation of W dust in the plasma chamber. According to the scenario for a Loss Of Vacuum Accident (LOVA), in the case of confinement failure dust is released, which can lead to occupational or accidental exposure.

Methods

For a first evidence of potential risks, fusion devices relevant W dust has been produced on purpose, using a magnetron sputtering gas aggregation source. We aimed to assess the in vitro cytotoxicity of synthesized tungsten nanoparticles (W-NPs) with diameters of 30 and 100 nm, on human BJ fibroblasts. That was systematically investigated using different cytotoxic endpoints (metabolic activity, cellular ATP, AK release and caspase-3/7 activity) and by direct observation with optical and scanning electron microscopy.

Results

Increasing concentrations of W-NPs of both sizes induced cell viability decrease, but the effect was significantly higher for large W-NPs, starting from 200 μg/mL. In direct correlation with the effect on the cell membrane integrity, high concentrations of large W-NPs appear to increase AK release in the first 24 h of treatment. On the other hand, activation of the cellular caspase 3/7 was found significantly increased after 16 h of treatment solely for low concentrations of small W-NPs. SEM images revealed an increased tendency of agglomeration of small W-NPs in liquid medium, but no major differences in cells development and morphology were observed after treatment. An apparent internalization of nanoparticles under the cell membrane was also identified.

Conclusion

These results provide evidence for different toxicological outputs identified as mechanistic responses of BJ fibroblasts to different sizes of W-NPs, indicating also that small W-NPs (30 nm) display lower cytotoxicity compared to larger ones (100 nm).

Low Blue Dose Photodynamic Therapy with Porphyrin-Iron Oxide Nanoparticles Complexes: In Vitro Study on Human Melanoma Cells

The purpose of this study was to investigate the effectiveness in photodynamic therapy of iron oxide nanoparticles (γ-Fe₂O₃ NPs), synthesized by laser pyrolysis technique, functionalized with 5,10,15,20-(Tetra-4-sulfonatophenyl) porphyrin tetraammonium (TPPS) on human cutaneous melanoma cells, after only 1 min blue light exposure. The efficiency of porphyrin loading on the iron oxide nanocarriers was estimated by using absorption and FTIR spectroscopy. The singlet oxygen yield was determined via transient characteristics of singlet oxygen phosphorescence at 1270 nm both for porphyrin functionalized nanoparticles and rose bengal used as standard. The irradiation was performed with a LED (405 nm, 1 mW/cm²) for 1 min after melanoma cells were treated with TPPS functionalized iron oxide nanoparticles (γ-Fe₂O₃ NPs_TPPS) and incubated for 24 h. Biological tests revealed a high anticancer effect of γ-Fe₂O₃ NPs_TPPS complexes indi-cated by the inhibition of tumor cell proliferation, reduction of cell adhesion, and induction of cell death through ROS generated by TPPS under light exposure. The biological assays were combined with the pharmacokinetic prediction of the porphyrin.

Abstract P1-05-01: The epithelial to mesenchymal transition: Identifying a signature of recurrence in ductal carcinoma in situ

Background: The epithelial to mesenchymal transition (EMT) plays a critical role in the progression from non-invasive to invasive breast carcinomas (IBC). It is characterized by alterations in gene expression, changes in cellular polarity, the disruption of tight junctions; production of metalloproteinases, transforming growth factor-β (TGFβ) induction, expression of cancer stem cell markers, hypoxia, decrease in e-cadherin expression, along with other molecular biological events. Several transcription factors including ZEB1/2, TWIST1, SNAIL1/2, FOX family, GATA4/6 are involved in the process. There is a need to identify the molecular events driving the progression of ductal carcinoma in situ (DCIS); and to derive a signature that differentiates DCIS lesions that have the potential to recur as a subsequent DCIS, an IBC, or to not recur. To catalog the changes associated with EMT that may reveal a clinically relevant signature of progression from DCIS to DCIS or IBC recurrences using a panel of 200 genes related to EMT.

Methodology: RNA was extracted from formalin-fixed paraffin embedded (FFPE) sections of pure primary DCIS lesions representing three categories of outcome: those that did not recur; those that recurred with a subsequent DCIS; and those that recurred with invasive cancer. RNA abundance profiling was performed using Nanostring platform and data processing using an R statistical environment. Levels of mRNA abundance were modelled as a function of recurrence status. Coefficients were fit to terms representing the effect and the standard errors of the coefficient were adjusted with an empirical Bayes moderation. Model-based t-tests were then used to test if the coefficients were significantly different from zero.

Results: Using a technical control sample, pairwise comparisons across three replicates showed high correlation (ρ=0.99, Pρ<2.2x10-16 for all 3 comparisons), suggesting the robustness of the assay. In our preliminary survey of 45 patients across the three groups, we have identified a number of genes that showed differential mRNA abundance levels between patients who recurred (either DCIS or invasive recurrence) vs. those who did not recur. Using Random Forest analysis in a leave-one-out cross-validation approach, we were able to obtain a classifier with a sensitivity of 82% and specificity of 58%. Based on these initial findings, an additional 200 samples have been processed to support these initial findings.

Conclusion: The current literature provided increasing evidence that transcriptomic patterns reflecting the EMT may reveal novel biomarkers and elucidate molecular mechanisms leading to improved prognosis. Among breast carcinomas, differential expression of the EMT genes has been associated with a worse outcome, among estrogen receptor-negative and basal-like carcinomas. However, the understanding of the role of EMT genes in DCIS is limited; therefore, to elucidate whether the EMT plays a role in the progression of DCIS, we have designed an EMT gene panel that also includes genes that are significant prognosticators for IBC, including ER, PgR, Ki67 and HER2. In an exploratory analysis of cases trained based on clinical outcome, the sensitivity for predicting recurrence (whether DCIS or invasive) was 82%.

Citation Format: Felipe Lima J, Yao CQ, Yan F, Dion D, Quintayo MA, Lungu I, Nofech-Mozes S, Pruneri G, Viale G, Boutros PC, Bartlett JMS, Bayani J. The epithelial to mesenchymal transition: Identifying a signature of recurrence in ductal carcinoma in situ. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-05-01.